Proceedings of the Finnish Dental Society. Suomen Hammaslaakariseuran toimituksia最新文献

This communication focuses on the participation of accessory cells in the initial recognition and processing of antigenic substances in the dental pulp. Immunohistochemical analyses have demonstrated the presence of two types of accessory cells--one with a dendritic morphology located in the periphery of the pulp and one with a macrophage-like appearance located more centrally. Functional studies in vitro have provided evidence for the dendritic cells being the most significant of the two cells regarding their capacity to induce T-cell proliferation. Studies on ontogeny have revealed that the appearance of pulp accessory cells is delayed compared to other peripheral tissues. In experimentally induced pulp lesions a rapid increase of cells with morphologic and phenotypic features similar to normally occurring accessory cells was found. These data demonstrate that the dental pulp contains the necessary cellular constituents to mount an immunologic defense reaction. Future studies should focus on elucidating possible interactions between these immune cells and the neurovascular system of the pulp.

Hypersensitive dentin appears to be mainly the result of an activation of the dentinal pain fibres, the A-fibres, at the pulpal wall. The stimuli which activate these nerves are primarily those which remove fluid from the dentinal tubules and mobilize capillary forces, causing a rapid outward flow. Application of a cold stimulus causes the fluid to contract, resulting in a similar rapid outward flow in the pulpal region of the tubules. Hypersensitivity to cold is also marked when there is a fluid-filled gap containing bacteria in the tooth. Experiments have shown that a freshly exposed dentin surface with patent tubules is more sensitive than a surface contaminated by a smear layer. Inflammation in the adjacent pulpal region can also increase sensitivity. The development of hypersensitive cervical and occlusal surfaces is due to mechanical and acidic effects from the oral environment, toothbrush abrasion, erosive components in the diet, plaque and bacterial invasion of dentin. Sometimes dentin is exposed by restorative therapy and occasionally eccentric occlusal loads can contribute to hypersensitivity. The sensitivity may persist unless the open tubular apertures are sealed.

A current Med-line search from 1966 to present cited over 344 juried publications employing the term microleakage. Dentistry recognizes microleakage as a multifaceted biological phenomenon. Brännström et al. (1967), Trowbridge (1982), Närhi (1983), and others have reported the sensory component of microleakage as a consequence of hydrodynamic fluid movement within the dentinal tubule complex. This movement of dentinal fluid has been demonstrated to displace nociceptive receptors which stimulate the nerves of the Group A fibers which run and terminate within the odontoblastic layer (see Matthews 1992). Penetration of oral fluids, bacteria and their toxic products within the preparation-material interface following material insertion accounts for the pathological component of microleakage (Browne and Tobias 1986). Continued microleakage of bacterial infiltrates eventually present as an inflammatory process which may initially signal the dentin complex to respond by deposition of a hypermineralized or sclerotic dentin. The pulp-dentin interface will repair with a specialized zone of reparative dentin. An overwhelming carious lesion often results in pulp infection and eventual necrosis. Vital dentin is an extension of the pulp, presenting the first line of defense to the consequences of microleakage. Recent publications have demonstrated that microleakage of dental materials in non-exposed and exposed pulps is a function of controlling bacterial infection. In an exposed mature dental pulp, the mesenchymal tissue permits the reorganization of pulp tissue and regeneration of a new dentin bridge in the presence of a biological seal. New odontoblastoid cells appear to regenerate from deeper pulpoblasts in the presence of various dental materials, apparently without an epithelial stimulating factor (Yamamura 1985). This inherent healing of the dental pulp and regeneration of a new dentin bridge is expressed in the presence of various dental materials, but only in the absence of bacterial infection. Data which evaluates the biological deposition of reparative and dentin bridges as either repair or regeneration are presented as a basis for considering the clinical selections of dental materials. Recent data demonstrate that dentin and pulp healing are ensured when a proper biological seal is provided to control and prevent microleakage.

Fifty-six patients with 86 benign oral soft-tissue lesions were treated with CO2 laser surgery during a period of 48 months. The lesions removed included hyperplasias, papillomas, haemangiomas, mucoceles, lichen planus, fibromas, condylomas and lingual frenula. All clinical diagnoses except that of lingual frenulum were verified histopathologically. The lesions were excised using the laser to obtain biopsy specimens. However, in some cases it was felt more appropriate to excise biopsy material from the most characteristic part of the lesion first, then to destroy the rest of the lesion. Treatment was undertaken in one session under local anaesthesia without premedication. No patient received antibiotics or anti-inflammatory drugs after operation. The lesions were operated on freehand using a handpiece and laser power ranging from 6 to 10 W in continuous mode. The beam in focus was 0.2 mm in diameter, which allowed fine dissection. There was no bleeding from the laser wounds, and no need for suturing. Removal of the lesions using the laser was fast and easy. Healing took place with minimal post-operative discomfort, and without visible scarring. The results of this study suggest that use of a CO2 laser leads to a level of precision similar to and sometimes better than that of a scalpel in the treatment of benign oral soft-tissue lesions. The laser beam could be used to obtain biopsy specimens without tissue destruction.

Evaluation is carried out to ascertain the value of something, or to compare accomplishments with some standard. Its purpose is to judge and improve the quality, effectiveness and efficiency of services. Oral health services for adults have been dominated by demand-led private practice arrangements. Classic programme evaluation, including assessment of appropriateness, adequacy, effectiveness, efficiency and side-effects has not been possible because neither objectives, nor activities to attain them have been defined. After presenting some evaluative studies of the past, this paper outlines one monitoring and evaluative strategy based on the mixed-scanning theory of planning. The strategy consists in defining a few oral health status and behavioural goals for four selected age groups of adults. Information concerning background and outcome variables is then collected at predetermined intervals of time from random samples of the adult population using a comparatively simple survey strategy. In order to keep the work-load and resource expenditure within reasonable limits, the periodic monitoring surveys would need to be supplemented by ad hoc studies for specific health services research purposes. The periodic surveys would be used to show the extent of goal attainment at predetermined points in time; the ad hoc studies for testing hypothesis about causal associations.

During dental treatment temperatures can be reached which might possibly damage the tooth pulp. To determine the effect of both thermal stimulation on pulpal microcirculation and local anesthesia on thermoregulation we measured the pulpal blood flow by using laser Doppler flowmetry. Experiments were carried out on lower incisors of Wistar rats anaesthetized with thiopental. The rats were divided into three groups, with one remaining untreated, and the others being either desensitized with capsaicin or sympathectomized with guanethidine. In a range between 33 degrees C and 42 degrees C there was no substantial change in blood flow, which, however, was the case below 33 degrees C. Up to 49 degrees C an increase could be recorded in both untreated and guanethidine pretreated animals, whereas the capsaicin groups showed almost no reaction. This increase in blood flow can be blocked reversibly by local anaesthesia. For this purpose we tested articain 5% and mepivacain 3%, both without constrictor. Intravital microscopic studies show that the temperature related increase in blood flow is also associated with plasma extravasation. From these results we draw the conclusion that pulpal thermoregulation is linked to nociceptive sensory neurons and can be described as "neurogenic inflammation".

We have recorded the flow of fluid through exposed dentine in cat canines. The effects on this flow of electrical stimulation of the cervical sympathetic trunk (CST) and of the inferior alveolar nerve (IAN) were investigated. In some preparations, pulpal blood flow was also monitored with a laser Doppler flow meter and the compound action potentials evoked by IAN stimulation were recorded from the tooth. CST stimulation (0.5-5/s) resulted in a significant decrease in the rate of outward flow of fluid through the dentine or, with the higher frequencies tested, a reversal of the flow. CST stimulation also produced vasoconstriction. IAN stimulation caused a significant increase in the rate of outward flow of fluid from the dentine. This effect required the recruitment of A delta fibres: A beta fibres alone had no effect. Pulpal vasodilatation occurred with the same threshold. Mechanical stimulation of dentine in an acutely denervated tooth also caused vasodilatation, indicating that pulpal afferents were involved. The results show that the rate of fluid flow through dentine, and hence the rate of inward diffusion of chemicals from the oral cavity, can be influenced by changes in the state of the pulpal microvasculature.

The mechanisms by which pain develops in carious teeth are poorly understood. The variability of dentin and pulp responses to carious attack is probably the cause for the variations in the pain symptoms presented by patients. This article is a review of the available data regarding the changes that dentin and pulp undergo in carious teeth. Such changes are discussed in relation to their possible influence on intradental sensory nerve excitability. Special emphasis is given to the various bacterial metabolites produced and accumulated in carious dentin and their ability to modulate pain symptoms from carious teeth.

To combat dental caries, a chemical has been sought that possesses stronger antimicrobial properties than fluoride in support of its physicochemical tooth-protecting properties. These searches have led to several agents, of which chlorhexidine (CH) appears most effective. To reduce local side effects of the well-known 0.2% CH mouthwash, a 0.05% CH gluconate + 0.04% NaF solution, pH 5.9, has been developed. Use of this combination over a 2-year period resulted in a 53% reduction in caries increment and a 75% reduction in gingival bleeding, i.e. a clear duality of prevention of oral disease (Luoma et al. 1978). Staining of teeth was minimal and easily removable in about one third of the subjects. To lessen the contribution of patients, chlorhexidine gels, without but more especially with fluoride have been professionally administered. Reductions in salivary mutans streptococci after short periods of gel applications have been found to persist longer than reductions after brief periods of mouthwashing. Reductions of approximal caries increment by about 50% in children, and root surface caries in adults have been obtained through use of CH gels. The effect on root surface caries in adults was equal to that obtained through use of local fluoride applications. Dental CH varnish seems promising, especially because a very short contact time with a tooth may be sufficient to reduce mutans streptococci. No simultaneous effects against caries and gingivitis of CH gels or varnishes has been reported. Comparisons of CH solutions, gels and varnishes, with or without fluoride, in relation to their potentials for preventing oral disease in subjects at risk remain to be accomplished.

The role of vitamin C in maintaining mucosal health is poorly documented. The purpose of this study was to examine the presence of oral mucosal lesions in subjects with low ascorbic acid (AA) levels in plasma. AA plasma levels of 843 working elderly people in six rural villages in Eastern Finland were determined. All subjects with low plasma AA levels (< or = 25 mumol/l) (n = 106) formed the study group. Controls with normal AA levels (> or = 50 mumol/l) (n = 103) were drawn from the same population. They were matched for age, sex and number of teeth. Oral mucosal lesions in all subjects were recorded clinically using a double-blind method in all subjects. Petechias, leukoplakia and lichenoid lesions were the commonest lesions of the oral mucosa. Only in leukoplakia there was a statistically significant difference between the groups (p < 0.01). Smokers had more leukoplakia than non-smokers. The prevalence of leukoplakia was higher when smoking was combined with AA deficiency.